| 摘要 |
Detection of gaseous volatile analytes includes immersing a sensor element of a gas-equilibrated volatile-in-liquid detector in or close to an aqueous fluid, enabling analyte flow through a vapour-porous membrane 6 into an otherwise closed gas sensing chamber 10b to achieve near chemical equilibrium between the analyte in the chamber and the concentration of analyte in the adjoining liquid, and measuring a signal from the sensor 11 (photoionisation detector (PID)) in response to the partial pressure of the analyte with the gas sensing chamber without the sensor significantly altering such equilibrium. The gas-equilibrated detector comprises chamber 10b having an orifice 11a closed by a hydrophobic, vapour-porous membrane 6, sealed to the periphery 11c of the orifice 11a. Membrane 6 is also sealed 2a to an external wall of a surrounding sensor enclosure 2 and forms an entry point to a second gaseous enclosure 12 external of the gas-sensing chamber 10b. |
